OBJECTIVE To reanalyze the mechanism of accommodation in the primate eye in light of proposed novel mechanisms RESULTS The classical understanding of the primate accommodative mechanism was supported by our studies DISCUSSION Accommodation and disaccommodation were studied in cynomolgus and rhesus monkeys using both pharmacological stimulation and midbrain electrical stimulation. Movements of the ciliary processes and lens were imaged using goniovideography. Movements of the ciliary muscle and lens equator were imaged using ultrasound biomicroscopy. Videographic analysis showed the ciliary muscle moves forward and axially during accommodation releasing resting tension on the anterior zonular fibers, increasing tension on the posterior zonular fibers and moving the lens equator axially away from the sclera. During disaccommodation the ciliary muscle is pulled back to its resting position by the elasticity of the choroid and the posterior zonular fibers; increased tension on the anterior zonular fibers pulls the lens equator back towards the sclera. FUTURE DIRECTIONS Further analysis will be done on images recorded from the surgically manipulated eyes to determine the role of the ablated structures in the accommodative process. KEY WORDS ciliary muscle, lens, zonule, ultrasound, disaccommodation FUNDING NEI EY10213, Johnson & Johnson PUBLICATIONS Glasser A, Kaufman PL The accommodative mechanism of primate eyes revisited. Invest Ophthalmol Vis Sci 39(4):S311, 1998 (ARVO Abstract). [A] Glasser A, Kaufman, PL The Mechanisms of Presbyopia. In Refractive Surgery 1998 Reshaping the Future. American Academy of Ophthalmology Subspecialty Day 1998 Series, pp 141-146, 1998. [J]